Laundry dryers



June 14, 1960 c. F. CZECH 2,940,179

LAUNDRY mamas Filed Sept. 4, 1956 s Sheets-Sheet 1 karma-fora WA l/% June 14, 1960 c. F. CZECH 2,940,179

. LAUNDRY DRYERS Filed e t. 4, 1956 s She ets-Sheet 2 62 38 I MN I 72 B 4 z2 7| m o June 14, 1960 Filed Sept. 4, 1956 c. F. CZECH 2,940,179

LAUNDRY DRYERS 3 Sheets-Sheet 3 c1 Herd F==7 Czeck United States Patent j LAUNDRY DRYERS Filed Sept. 4, 1956, Ser. No. 607,626 r 13 Claims. (Cl. 34-47) The invention relates to laundry dryers generally and is more particularly concerned with dryers of the type having a closed air circulating system. i

One object of the invention is to simplifythe construction and increase the operating efficiency of dryers of the above character.

' A more specific object is to provide an eficient and dependable closed circulating system dryer of simple, rugged construction that can be manufactured at re1a-' tively low cost.

-,Another object is to provide a dryer in whichv only a predetermined portion of the circulating air is passed over a-relatively cold condensing surface to reduce its moisture content before it is heated and returned to the drying chamber.

Another object is to provide improved moisture condensing means for laundry dryers! Still another object is to provide improved means for removing lint from the air circulating in the dryer.

Other objects and advantages of the invention willbecome apparent from the following detailed description of the preferred embodiment illustrated in the accompanying drawings, in which Figure 1 is a rear view of a dryer embodying the features of the invention, the rear part of the cabinet and portions of the interior partitioning structure being removed to show details of'the air circulating system.

Fig. 2 is a vertical sectional view of the dryer shown in'Figure l.

Fig. 3 is a fragmentary perspective view of the casing structure defining the chamber in which the circulating air is treated to reduce its moisture content and increase its temperature.

Fig. 4 is an enlarged sectional view taken in a plane substantially on the line 4-4 of Fig. 1.

While a preferred form of the invention has been shown, and will be described in detail herein, this is not intended to limit the invention to the particular con-' struction illustrated but the intention is to cover all modifications and adaptations falling within the spirit' and scope of the invention as explained in the appended claims.

Referring to Figs. 1 and 2 of the drawings, the dryer selected to illustrate the invention has a generally rectangular cabinet enclosing the operating parts of the appliance, including a cylindrical tumbler or drum 1! which defines the clothes dryingchamber. The drum 11 is supported in the cabinet for rotation about a horizontal axis and, in operation, is rotatably driven by a'motor M. Support for the drum is provided in this instance by a pair of resilient rolls 12 spaced apart laterally in the cabinet and positioned to engage the periphery of the drum adjacent its forward end. At its rear end the drum is supported by a bearing 13 secured to the rear drum wall and running 'on a shaft 14 carried by suitable supporting structure in the cabinet to be discussed later.

The drive for the drum 11 in this instance is through v v one of the rolls 12. As shown in Fig. 2, the driving roll 12 is mounted on a shaft 15 journalled at one end? in a bearing 16-carried on a transverse positioning mem' ber 17 forming a part of the cabinet 10. At its other end the shaft extends through a bearing 18 (Fig. 1). carried on a vertical panel member, 19 provided in the; cabinet; The shaft 15 is fitted with a driving pulley- 29 aiined in a common plane with a-pulley 21. on the: shaft of the motor M and a pulley 22 journalled-on theshaft 14 A Vbelt 23; is trained over all three pulleys}: the belt b eing maintained under tension by the weight of the motor which is mounted on a swinging bracket 24 as shown in Fig. l. 1

In accordance with one-aspect of the invention,'-ther tumbler drum 1'1 embodies novel features ofconstruction which provide for more ,efiicient circulation of air through the clothes during the drying operation and which further provide for the effective removal of lint from the circulating air. The drum is preferably constructed of sheet metal and, as shown in'Fig. 2, comprises a cylin-,

drical peripheral wall 25, a front end wall as and a rear end Wall 27. To provide for the circulation of the air in a closed circuit, the peripheral wall of thedrum is' imperforate and the front Wall is also imperforate, except for a central access opening 28'. The opening 23, in this case, is bordered by a flange 29 and, when the drum is assembled in the cabinet 10, the opening 28 is substantially alined with an opening 30 in the front wall of the cabinet. The latter opening is provided with a hinged door or closure 31. It will be understood that the openlugs 28 and 30 are dimensioned to permit convenient loading and umoading of thevdrum. While they have been shown spaced apart in the present instance, it will be understood that a sleeve or liner may be provided, if desired, to prevent articles being placed in orremoved= fromthe drum from falling into the cabinets. To provide for the admission to'and exhaustof air from the drum, the back wall 27 is provided'with spaced forarnina'te areas which may be in the form of screened" openings or of groups of closely spaced punched holes One .of the foraminate areas is annular and is located? adjacent the marginal edge of the wall. As shown,- this area is defined by a series of closely spaced punched holes.35 and is related to the other elements of the air: circulating system to. be described presentlyso as to constitute the air inlet for the drum. l

The other foraminate area, which in this instanceconstitut'es the air outletfor the drum, is preferably roughly circularin form and located centrally of the wall 27,"that is, coaxial with the drum. This area is defined bya s'eriesof" closely spaced punched holes 36. For convenience of assembly the wall member 27 is formed With a'marginal flange 38 adapted to fit into the cylin drical wall member 25 as shown.

The end wall member 27 is also formed to provide for the mounting of a lint-screening device or lint trap 40 in a location for eifectively'removing lint to prevent any accumulation in the air circulating system. For'this purposethe central portion of the wall member 27 is offset or pressed'outwardly in the form of acylindrical boss 41 to define a relativelyshallow cylindrical recess 42 opening to the interior of .the' drum; The support bearing 13 is secured to this'boss as by radially'extendingarms 43 which are attached to-the wall member bybolts or suitable fastening elements. As will be seen byreference to Fig. 2-of the "drawings the central portion'of? the boss 41 is formed with agclearance opening for the; shaft 14 which extends through the bearing 13 and com: pletely throughthe lint trap recess .42 with its inner end; projecting into the drum. i 1:95 :lh l n tr p .4 i s P e red; .f ZItFQmPI SQ- a circular front plate 44 dimensioned to cover the lint trap V and is dimensioned to fit tightly within the flange of the plate. The screen element and the plate 44 are 'both centrally aperturedto accommodate the shaft 14 and a nut 49 threaded on the end of theshaft serves to hold the trap-securely in place. The nut is readily accessible through thejaccess-openings in the cabinet and drum; t'hus' e'nahling the trap to be easily removedefor cleaning 7 out accumulated lint. i e

For cooperation with the drum 11 the invention provides a structure'defining an air treating chamber or passage completing the closed air circulating path. This structure is characterized by its'compact and simple construction and by its high operating efliciency in terms of power consumption. The compactness of the structure; of course, permits substantial reduction in the overall size of the cabinet which, together-with the sim- 7 plicity of construction, materially reduces manufacturing costs. The efliciency of the circulating system is reflected by its ability to remove moisture from a load ofclothes with a minimum expenditure of power and in a relatively short time. In addition, the dryer is rendered much more suitable for household use since the discharge of moisture or lint laden air is avoided without resorting to outside venting of the dryer.

.As shown in Fig. 2 of the drawings, the cabinet 10 is divided transversely by .an upright partitioning'member 50, preferably a sheet metal panel, suitably attached-Ito the wall of the cabinet andcxtending across the rear of the 'drurn.11.. A'circular'sectionsl of the partitioning member. is formed rearwardly to .definean annularshoulder-52 .ofisubstantially the same diameter as the drum and coaxial with it;' Centrallyof thesection 51 is an of the treating chamber and the passage -57--is spir-ally coiled about thefanspaee made generally circular as shown in Figs. 1 and 3. Thus, a chamber of substantial length is obtained, providing ample accommodations for the condenser and the heater, yet occupying a minimum of space in the back of the cabinet. In the exemplary chamber onenend lwallof the air treating chamber is formed by thepar'titionin'g member 50 while the side wall and the internal partitioning dividing the fan.cornp artrnent from the pas sage57 is formed by a si gl elo ga d h t m t i t f n fifi. b m'imQfsPiIHI configuration. An outercover plate (Fig.2) closes the other end of the chamber. For convenience of attachment to the .endsuvallsl the strip 66may'ihef0rmed with flanges 67 (Fig. .4) at opposite sidesior spot welding or otherwise suitable""attachmentto the members 50 and 67.

As will be seenby reference to Fig. 1 of the drawings,

' the passage :-57 of :theairtreating chamber opens at one opening'dimensioned .to receive the boss 41 on the end 1 wall .of the drum. A sealing :ring 53 on the drum coact ing with the shoulder .52'and a sealing ring 54 on the partitioning member coacting with :the boss 41 seals the space between'theend of the'drum'a'nd the partitioning member. I V

Disposed at the rear of the 'partitioning'member and preferably built directly .upon it is a structure defining the air treating chamber above mentioned and connected to form a closed circuit with the drum 10. Airlwithdrawn from the drum. is circulated through this chamber and treated to remove a part of :the moisture picked up from the contents of the .drum'and to-raise the temperature of the airbefore returning it to the drum for further drying ,of the .drum'contents; .In accordance with'the invention th'e'air .treating chamber isconstructedi'to provide a generally cylindrical fan compartment ;56.disposed V coaxially of the drum 11. and opening tovan elongated R 5age57 thatghas its'toutle't positioned Ito register with the-air inlet of thezdrum; The arrangement-is suchkthat enters the compartment 56..from the central portion f the drum through'the :perforationsifidinf the :hoss '41 afterpassing through the lint trap 40 asindicatedmyzthe arrows 58in Figs. 25and'i3..of theadrawings. r

The air drawninto fthe fanrcompartmentifi, .or.a pre determined portionof it, 'is then directed through the passage 57 in which is "mounted a condens e'r till and- 'a heater 61 The heated-air-is-i'eturned to the tir-um by way 'of an opening 62 in the partitioning memberas indicated "by the arrows 63 in'Figs. 2 and -3. Asvvill beseen by reference to'Figs. 1- "and- '3 of the drawings, the'opening 62 is arcuate inform andjsj-positioned tosideofxthelfanspace56 and extendsaround that space approximately 270. The entrance to the passagefrom the fan compartment is formed by bending the inner end of the strip 66.0utwardly as at.68 andlocating it in spaced relation to the opposite wall of the passageijiThe end portion68 thus, in eifect, constitutes-a vane for directing the air flow towardtthe outer wall of the passage. The other end portion v69 of the Wallstrip 66 is bent inwardly at approximately right angles :toabut the adjacent outer face of the wall strip and thuslformthe end wall for the passage. Preferably, the opening 62 in the partitioning member 50 isllocated adjacentthe closed end of the passage. The heaterf61,.herein shown as a resistance coil, is supported in the passage adjacent the opening 62:50 that thecirculating air passesover it on its way to the openingand the tumbler drum.

Circulation of air is maintained through the air treating chamber and tumbler drum by a. rotatably driven multi-bladed blower or fan element 70 mounted in the' fan compartmentifi ofthe air treating chamber. Aszshown 1 Fig. 2, the fan element has .a 'hnb'llkeyed or otherwise non-rotatably fixed on a sleeve 72 whichservesas '.a hearing for the shaft14 and which, in turn, is journalled ill a bearing 73 carried on the cover. plate 67. Thexlriving pulley 22 hereinhefore mentioned is .keyedi-to the project ng end .of the sleeve element 72. a

In the-exemplary dryer the condenser fiilislocated adjacent the entrance to the passage 57, that is,w at. its junction with the fan compartment 56 so that the air entering the passage is subject to the cooling aetioniof the condenser. The condenser in its preferredform com prises an elongated strip 75 of sheet metal .ofsubstantially the same width as the wall member 66::and disposed in register with the annular series of apertures E3? in the end wall 27 of the drum T For simplicity 'andcompactn the fan compartment the passage.

face-to-face contact :with such wallmember as shown in Figs.3 and 4. Asshown 1herein,'the condenser strip 75 extends upwardly from approximately the lowermost portion of the passage 57- toa point spaced approximately 65 therefrom. The strip is preferably corrugated transversely so as to present a maximum- .surfacearea to the air circulating through the passage.

The upper end portion 76 of the strip 75 is generally funnel-shaped and it is disposed below an inlet opening 77 in the outer passage wall; Cooling water is directed through the openings77 from a nozzle .78 or' :the like an: der control of a suitable valveV which may be opened and closed manually'or by a solenoid 7,9. .-A*screen 80 is desirably provided in th evopening '77 toprevent the entry of any foreign material.

The water introduced into the air treating chamber through the opening, flows down the back of the-con denser strip 76 and theadjacent wall of the passageand out through a discharge'opening '81 at the lowest point of The condenser strip is thus maintained at a temperature substantiaily below that of "theair circulating through the passage. Accordingly, as the'w'arm moist air flows over the strip it is cooled anda'substantial portion of the moisture in the air condenses on the strip. The condensate flows down the strip and is discharged through the opening 81 along with the cooling water. Any lint escaping through the lint trap 40 will tend to collect on the condensing strip and, of course, will be washed down through the discharge opening with the condensate. The cool dry air continues along the passage and is heated to the temperature required for efiicient drying by passing over the heater 61 before entering the tumbler drum 11.

Under ordinary operating conditions the air circulating in the dryer does not become completely saturated with moisture in a single passage through the tumbler drum. I have found that a substantial reduction in the power required for heating purposes can be realized without materially increasing the length of the drying cycle by subjecting only a portion of the circulating air to the action of the condenser. This is particularly eiiective when the cooled dry air is then thoroughly mixed with the uncooled portion of the air and the entire mass passed over the heater before recirculation through the tumbler drum.

In the improved dryer the by-passing of a portion of the air around the condenser is effected by providing a by-pass opening in the chamber wall 66 at a point between the entrance to the passage 57 and the outlet opening 62 from the passage to the drum. This by-pass opening is conveniently formed by transversely slotting the wall member 66 at the appropriate point and striking out the adjacent portion to form a deflecting hood. The size of the opening 85 may be varied as required by the particular conditions under which the dryer is to be operated. Thus, for ordinary domestic usage, it has been found that satisfactory operation is obtained with an opening dimensioned to by-pass approximately 30% of the circulating air. The air discharged through the opening 85 as indicated by the arrows 87 meets the air stream flowing through the pas-' sage in the vicinity of the heater 61. This insures a thorough mixing of the warm and cold air in its passage over the heater and before passing through the opening 62 to the drum.

In the operation of the improved dryer the wet clothes or other fabrics to be dried are loaded into the drum 11 through the access openings 30 and 28 and the door 31 is closed. By operation of a suitable starting switch, the motor M is started and the heater 61 is energized. At the same time the valve V is opened "to direct a flow of cool-- ing water over the condenser 69.

Motor M rotates the drum 11 at a rate efiective to tumble the load and present the individual pieces to the drying air current in the drum. This air current is maintained by the fan 70 which draws air from the central portion of the drum through the lint trap 40 into the fan compartment 56. Part of the air is discharged from the fan compartment into the passage 57 where it is subject to the action of the condenser 60 to reduce its moisture content. The remainder of the air drawn from the drum is discharged through the by-pass slot 85 to mix with the cooled and dryer air. The entire mass of air then passes over the heater 61 and through the outlet opening 62 and perforations 35 is the drum wall to the interior of the drum. Air circulation is maintained and the tumbler drum operated until the clothes reach the desired degree of dryness.

During-operation the moisture condensed from the air by the condenser 60 flows down the strip 75 to the discharge opening 81 through which it is discharged along with the cooling water admitted through the opening 77. The major portion of the lint picked up from the clothes being dried is caught in the lint trap 40 and any that passes through will tend to collect on the condenser strip 75 to be washed down by the condensate into the discharge 81.

When necessary, accumulated lint may be removed from the trap 40 by unscrewing the nut 49 and drawing the trap forwardly through the access opening of the drum. The screen portion of the trap is readily detachable from the perforated front-plate'44 since the parts are held" together frictionally by the resilient ring 47. The cleaned lint trap is then replaced and secured in place by 49. a

' It will be apparent from the foregoing that the inven tion provides a laundry dryer of novel and advantageous construction. structure defining an air treating chamber which is very compact and requires a minimum amount of space in the cabinet. The simplicity of construction and particularlythe use of a single narrow sheet metal strip for defining both the fan compartment and the elongated air treating:

passage materially reduces the cost of manufacturm The improved dryer is particularly well adapted for;

household use as discharge of moist air and lint into the room is completely avoided without resorting to outsideventing of the dryer. A simple yet efiicie'nt condenser makes it possible to maintain continuous circulation of air without interference with proper drying. Power consumption is reduced by subjecting only a portion of the air to the action of the condenser through the dryer. 7 I claim as my invention:

in its circulation 1. In a laundry dryer, in combination, an upright sheet member secured to the other edge of said strip, said.

' members and said strip defining an air treating chamber.

comprising a generally circular fan compartment with an elongated passage opening. therefrom and spirally coiled about the compartment, said partitioning member: having one opening communicating with said compart-g ment and another opening communicating with said pas-r sage adjacent the end remote from the compartment, a. fan element mounted in said compartment operative to draw air through said one opening and discharge it by; way of said passage through said other opening, and .a'

heating element mounted in said passage adjacent said other opening.

2. In a laundry dryer, in combination, an upright sheet metal partitioning member, an elongated metal strip bent into generally spiral configuration and secured at one edge to one face of said member, a sheet metal cover member secured to the other edge of said strip, said members and said strip defining an air treating chamber comprising a generally circular. fan compartment with an elongated passage opening therefrom and spirally coiled about the compartment, said partitioning member having one opening communicating with said compartment and another opening communicating with. said passage adjacent the end remote from the compart' ment, a fan element mounted in said compartment opera ative to draw air through said one opening and dis-.

charge it by way 'of said passage through said other opening, a condenser mounted in said passage adjacentthe opening from said compartment, and a heating element mounted in said compartment adjacent said other opening.

3. In a laundry dryer, in combination, an upright sheet metal partitioning member, an elongated metal strip bent into generally spiral configuration and secured at one edge to one face of 'said member, a sheet metal cover member secured to' the other' edge of said strip, said members and said strip defining an air treating chamber comprising a generally circular fan compartment with. an

elongated passage opening therefrom and spirally coiled about the compartment, said partitioning member having one opening communicating with said compartment and another opening communicating with said passage adjacent the end remote from the compartment, a fan element mounted in said compartment operative to draw air through said one opening and discharge it by way of said passage through said other opening, and a corrugated sheet metal strip supported in said passage adjacent its the nut The invention provides a simple sturd'y the passage adjacent said Vother'opening.

eam

V 1 iauct on iths id mpartment andin-face-to-tace contact with the outer walllof the passage, the outer Wall of the pas ge having an Open g adjacent the uppe n of the corrugated strip for the admission of a stream of water for coolingrthe-stiip, said outer wall also having an opening adjacent the lower end of the corrugated strip forj the discharge of cooling water andcondensate.

I 4- In a dry ye in com in n, a P of P- rightfi sh e .me lrrnember di p e in sp ced p rallel relati n, an el nga heet met l ship bent into generally spiral configuration interposed betwecntsaid'members andhaving its opposite edges secured thereto, Said members and said strip defining a generally circular chamber with an elongated passage spirally coiled. about it, the innner end of said .sti'ipheing positioned to define a1 ivopeni-ng irom said compartment tosaid passage and the other end of the strip being bentoverhto form the end wallvof the passage, one of said members having an air .inlet opening into said "chamber and an air uoutle't opening vadjacent the end'wallofT-said passage, a transversely. corrugated sheet metal: strip mounted in 'face-toface contact with the portion of said strip defining-the outer wall of said passage adjacent the opening from the compartment, and said strip ha'ving inlet and discharge openings respectively positioned for directing .a stream of coolingwater betweenrthe upper end of tne corruw gated stripand the adjacent wall of the passage and for discharging the water adjacent the lower end of the corrugated strip.

5. In a laundry dryer, inzcombination, an elongated sheet metal strip bent into generally spiral configuration to define a circular compartment opening into an elongated passage spirally coiled about the compartment, sheet metal members secured to opposite edges of said strip to constitute the other walls of the compartment and passage and spaced from said heating element, and blower. means mounted adjacent said first openingv operative to draw air-from the chamber through said first opening, said air returning to the chamber through said second opening, said passage being formed 'to direct a portion of the incoming air around said condenser and directly to said heating element.

9. In a dryer having a drying chamber closed at one end by 'a sheet metal wall having spaced openings .communicating with the chamber, a sheet metal strip secured to said wall and defining ,a generally spiral passage connecting said openings, a blower mounted adjacent one opening operative to circulate air through the chamber and passage, a corrugated sheet metalstripdisposed adjacent theinner face of said passage intermediate said openings, and means for directing a flow of cold'water between .said corrugated strip and the adjacent wall of the passage "to .c'onditionvthe corrugated stripifor condensing. moisture fromethe c'irculating'air, said 'striphaving an opening disposed adjacent'the lowest portion of the passage andtconstituting an outlet for the water.

10. In a laundry dryer, inscombination, a cylindrical drum having an end wall formed to provide a shallow cylindrical'recess coaxial with the drum, and a lint trap mounted in said recess comprising a generally cylindrical metal plate having a narrow internal flange dimensioned to fit within said recess, a resilient gasket on said flange passage, said strip being transversely slottedto provide for discharge of air into said :passageat a pointispaced substantiallyfrom the junction of theipassage with said compartment, one of said members having an inletxopening into said compartment and an outlet opening from said passage, a-fan element disposedin' said compartment, and-bearing means carried :by the other of saidmembers rotatably supporting said' fan element 6.'Allaundry dryer as defined in claim 5 i i-Which a' condenser is mounted in the passage betweenthe junction ofthe passage with the compartment and'the slot in the common wall betweenthe passageand the conipartment.

7. Ina laundry dryer, in combination, aniupright "sheet metal partitioning member, an elongated metal stripibent into generally spiral configuration and secured atione comprising. a generally circular fan compartment with an elongated passage openingtherefrom and spirallyicoiled about the compartment, said partitioning member having one opening communicating with said compartment and another opening communicating with said passage 'adja cent the end remote from the compartment, a fan ele ment mounted in said compartment operative to draw 7 air through said one opening and discharge it by way of said'passage through said other iope ning, said strip having a'transverse slotini-the' portion separating said compartment from said passage positioned to bypass a portion of the circulating air from the compartment to 8; In a dryer havingla generally cylindrical drying chamber, a wall member-adjacent one end of said chamber having a first opening .c'oaxially alinedrwith .the' chamber and a second opening "spaced laterally ofgsaid' firstopening, meansrcoacting-withgsaid wall member to define a generally spiral passage connecting saidtwo openings, a heating element mounted in said passager ad- 7 iaceutsaidse nd op niagra condenser mountedin said operative to efiect sealing engagement with the end wall of the drum and to retain the plate in closed relation to the recess, a cup-shaped element of fine meshed wire fabric, and a resilient ring mounted on the edge of said element and adapted to fit tightly within the flange of said plate to secure the element to the plate, said plate and the end wall of the drum within said recess being perforated to permit flow of air from the drum through the lint trap. l1. Ina clothes dryer, in combination, a cylindrical tumbling drum having an imperforate peripheralwall, a front end wall formed with a central access opening and a perforated rear wall, a boss formed in said rear end wall concentric with the axis of the drum defining a shallowcylindrical recess opening into the drum, a bearing secured to said boss externally of the drum, a shaft extending through said bearing and into the drum for supporting the drum, a lint screening device mounted in said recess, and a nut'threaded on said shaft for retaining said device in place. 7

12. In a clothes dryer, incombination, a cylindrical tumbling drum having an imperforate peripheral wall, a front end wall formed with a central access opening and a perforated rear wall, a boss formed in said rear end wall'concentric with the, axis of the drum defining a shallow cylindrical recess opening into the drum, a lint screening device removablymounted in said recess, and a perforated cover plate removably .mounted in said recess between said screening device and the interior of l3.In alaundryjdryer, in combinatioma sheet metal metal strip afiixed to said wall member externally of the'charnber defining a spiral passage centered about said opening, the offset portion of said drum havingaa series of openings aifording communication between the interior of the drum and said' passage, a fan mounted on and driven by said shaft to draw air from the chamber into said passage, said passage. having an outlet through said wall member ;for discharging air into said chamber adjacent the periphery of said drum, and a cup shaped screen .elfimentmounted in the ofiset at said one end of the drum recess, said screen element being operative to trap lint entrained in the air drawn from said drum into said passage.

References Cited in the file of this patent UNITED STATES PATENTS Shapter Aug. 11, 1953 10 Shewmon .L Apr. 27, 1954 Kachuck Sept. 21, 1954 Vetorino July 5, 1955 Steward Nov. 8, 1955 Pfleider Nov. 29, 1955 Worth Dec. 18, 1956 Reiter July 9, 1957 Geldhof Apr. 1, 1958 Conlee Apr. 1, 1958 FOREIGN PATENTS France May 27, 1953 

